Wayne, thanks for your reply. I tried to reply immediately after your's but was unable to log in and just now established a new account.
I had the Auto Nozzle Check turned off but it still was running a clean cycle. However, as often helps I just did a reboot of my mac and turned off the printer and back on again and the cleaning cycles have apparently stopped.
Regarding my comment about the matte black head. I'm glad I was mistaken about there being a separate head for each black. I should have known better but being I didn't I decided that maybe using the PK head and ink would result in correct prints. I'm at a loss as to why the misalignment of the heads could have been rectified by switching to PK from MK but I'm very glad it did. I had decided to not spend a large amount of money on having an Epson tech repair the 7900. I couldn't justify the expense of that repair for what I earn with the printer. So now I'm very happy that the 7900 is printing again. It will be interesting to see printing results when I do switch black ink types again. But for now I'm going to explore using PK inks and different paper types. I had been using different matte fine art papers for years so I'm excited to now explore more glossy alternatives. I've started with what seems to be a very reliable choice, Ilford Gold Fibre Silk. I used to use Ilford's Smooth Pearl so I'm curious to see how different prints on IGFS will be.